Control system



P. S. DICKEY CONTROL SYSTEM May 31, 1949.

2 Shets-Sheet 1 Original Filed July 24, 1940 May 31, 1949.

P. s. DlcKEY CONTROL SYSTEM 2 Sheets-Sheet 2 original Filed July 24,1940 Nv N 1| l Il.

NON

NON wNozoum Patented May 31, 1949 CONTROL SYSTEMi laul S; Dickey, EastCleveland,- OhimaSSignor to. Bailey Meter. Company, acorporation ofDela-y Walle @riginal application July 24, 1940, Serial No. 347,191.Divided and this application June 27; 1942, Serial No. 448,829

This invention relates to method and means for operating and controllingthe-operation of vapor generators; particularly vapor generators f thedrun'rless,v forced flow. type, having a fluid ilow pathincluding-one ormore long small-bore tubes, infwl'iioslflA the flow in the path isinitiated by the entrance of liquidlunder pressure at one end, andthe-exit of vapor-only at the other. end; characterized by an inflow `ofliquid normally greater than the outflow of vapor, the difference beingdiverted from the path intermediate the ends thereof;

Such a vapor generator having small liquid storageandoperated-With Widerange combustion devices for-ms a combination rendering practicalextremely high heat release rates with the consequentability toeconomically handle practically instantaneous. load changes from minimumto maximum, andvice versa, without heavy standby expensaand. isparticularly suitable for operating conditions such.. as marine service,where load variationsare of awdeI range and are required to `be `metsubstantially instantaneously.

The generator has a minimum liquid storage capacitywitha maximum` heatabsorbing surface so disposed and arranged as to be substantiallyinstantaneously responsive to rapid changes and wide diversities in heatrelease rate in the furnace. The heat absorbing surface is arranged inrelation to the path of the products of combustion and radiant heatingso thatrthe entering liquid is received at the cooler endof the path.Further, the vapor generator insofar as the passage oi combustion gasesis concerned has a continuously increasing resistance to gas flowthroughout the length of the passageway.

rEhe-heat absorbinglsuriace, or flow path for the working medium', iscomprised of` one or more long small-bore-tubes with an enlargement,preferably at they end. ofthe generating section, which acts asy aseparator` to. divide liquid and vapor. The vapor is then passed`through a superheater, whilethe excess liquid` carried through thetubes tor the purpose of. wetness and preventing scale deposit, isdiverted out of the separator under regulated conditions, as will; behereinafter set forth. Fromthe separator there is a normal continuousand an` additional' regulated spillover or diversion of a` part of theliquid entering the economizer under pressuraso that there is alwaysbeing `fed to and` through the economizer and vapor generating. sectionsmore liquid than can be convertedinto-vapor in asingle passagetherethrough, although the proportion of such excess liqudmay representbut a` small partei the total volumeV of fluid passing through, thevapor generator andis at mosttim'es only` suCient toinsure tubeWetnessand to carry oil; scale forming n'niterial.` Thegeneratingandsunerheating seotions are desirably arranged. `in separateflow paths. for the combustion. eases, and dempers" arranged in thesepaths are actuated by means responsive tothe discharge, steamtemperature for` n1aintaining4 predetermined temperature standards.r

An object of the invention is` to provide an automatic control, of. thesuperheatedv steam tem.- peratuije going` to, thesteam4 utilizingapparatus and in `particular to provide asystom wherein the tempera-turecontrolstandard for thesuperheated steam is automatically changed. when.conditions warrant or demandadifierent 'standard of temperature for safeandeicient Operation.

Another object is to provide for a` vapor generator a control systemVoperatingto. control the flow of combustion gases in parallel; pathsover generating and `S.uperheating sections. So as to maintain,predetermined temperature standards.

Further. objects` will become evident from a, study of the speolcationandA of the drawings, ll. Which; i

Fig. 1j is asectional. elevation `of avallo?, generator having `myinventionincorporated therein.

Fig. 2 is. al schematic ldiagram of the. vapor generator of Fig. 1` witha` control system operatins. to maintain temperatures of the. dischargedvapor at values` corresponding to predetermined load demands.

In the various drawings., identical. parts bear the samolefetencenumerals.,

The drumless forced, W vapor generator of the type to whichthepresentinvention may pref.- erably be applied is diagrammatically illustratedin Fig.. 1 to ndioatethe. arransementof heat absorting suriacesinseparatenow paths for combustion gases, andthe control, ofgas iiowAthrough the pathsbv damperaaswill bey described shortly.

The iiow circuitsv comprising the vapor generatingA surface`tangentially enterv` a bulge in the iluid ilovvy path, which isintheform of i a separating chamber 232 for dividing the liuid into liquidand vapor; the vaponpassing to `a superheater 242 and the excess liquid.being diverted from the fluid ilow. path through a pipe lV tothe hotWell or yto waste. This excess liquid;l may pass through heatexchangers, it desired.` A normal continuouswSpillover occurs.` throughthe` restriction` 2, While a` variable spillover occursthrough theregulating valve.

The heat source (Fig. 2) includesA an `oil burner 4 supplied by a pipe5, and an air chamber 6 supplied by a conduit l. Initial ignition of theoil iiring means is accomplished through the agency of an igniter means8, which is disclosed and claimed in the Patent 2,261,458 issued toErvin G. Bailey and Paul S. Dickey. The electrical control system andmechanism for actuating and controlling such ignition means is alsodisclosed and claimed in said patent.

Fig. l is a longitudinal sectional elevation of the vapor generatorhaving my improved controls associated therewith, and on this figure areindicated the relative locations of the burners, iurnace, and heatabsorbing surfaces. It is not believed necessary, in this application,to go into detail as to the construction and arrangement of the vaporgenerator further than is shown in Figs. 1 and 2, since the structure asshown is sufficient for a clear understanding of my invention. I haveindicated on Fig. 1 by name the various portions of the unit in sufcientdetail to allow an understanding of the general arrangement. Inparticular, attention is directed to what I term the superheat dampers 9and the generator dampers l0. Further and more detailed reference willbe made to these dampers and to their control throughout the specicationand claims. Suffice it to say here that a positioning of the damper Scontrols the passage of hot products of combustion through thesuperheaters, while a positioning of the dampers I controls the passageof hot gaseous products of combustion through a major portion of thegenerating surface and economizer surface. Thus, by a regulation of thetwo sets of dampers, the products of v combustion or the heating may beshifted more or less from or to the superheating surface for a controlof the iinal superheated steam temperature leaving the generator to thepoint of usage.

Referring now in particular to Fig. 2, I illustrate the fluid flow pathas a single sinuous` tube, to the economizer section 202 of which,liquid is supplied under pressure through a conduit from a pump, notshown, which may be of any suitable type. From the leconomizer sectionthe iluid passes to and through the generating section discharging intothe separator 232. From the separator, vapor passes to and through thesuperheater 242, leaving by the conduit 244. Products of combustion passsuccessively through the generating section comprising the furnace wall,superheater, and economizer and may contact a part or all of theseparator. In the embodiment illustrated in Fig. 1 of course a portionof the products of combustion may not contact the superheater but maypass over a second portion of the generating surface and over theeconomizer surface.

29 represents means responsive to liquid level within the separator 232and constitutes a pressure casing enclosing a mercury U-tube connectedacross the vertical elevation of the separator. A lloat is adapted torise and fall with the surface of the mercury in one leg and to thuscause a positioning of a pointer 30 relative to an index 3| to advisethe instantaneous value of liquid level within the separator.

The liquid level responsive device 29 further controls, through a pilotstem 48, the positioning of the variable spillover valve 3 in suchmanner that upon a rise in liquid level within the separator 232 above apredetermined elevation there will be a regulated opening of the valve 3to supplement the normal continuous spillover 2 to the pipe I.

Referring now to Fig. 2, I illustrate a temperature control system forthe boiler of Fig. 1. Herein I show the superheat dampers 9 and thegenerator dampers IB separately positioned by pneumatic actuators 83, 84respectively. A Bourdon tube 22, forming part of the temperature system,is sensitive to the total steam temperature leaving the superheater 242and passing through the conduit 244, and indicates by means of a pointer23 relative to the index 24 the value of a total steam temperature.Freely suspended from the movable end of the Bourdon tube 22 is a link85 carrying at its free end one end of a oating link SS, the other endof which is positioned by a motor 'l1 to one or the other of twoextremes of travel representing different temperature standards.Suspended intermediate the ends of the floating beam 86 is a pilot stem88 positioned relative to a pilot casing 81, adapted to establish airloading pressures effective upon the pneumatic actuators 83, 84.

The arrangement is such that as th-e pilot stem u8 moves downwardly theloading pressure in the pipe 8e gradually decreases, while the loadingpressure within the pipe gradually increases. Conversely should thepilot stem 88 move upwardly, then the loading pressure in the pipe 89gradually increases, while that within the pipe ed will graduallydecrease.

The arrangement of the control mechanism and of the dampers 9, ||l issuch that as one set of dampers tends to close the other tends to open,and vice versa. This arrangement provides that if the superheattemperature is above the desired value the superheat dampers 9 will tendto close, while the generator dampers lll will tend to open, thussending a greater proportion of the hot gaseous products of combustionthrough the generator and economizer portions of the ilow path and awayfrom the superheater portion.

Inasmuch as the Bourdon tube 22 vertically positions the pilot stem 88relative to a substantially Xed right-hand end of the beam 86, it willbe apparent that if said xed pivot for the beam 86 is moved to a newlocation by the motor then a given position of the stem 88 will beaccomplished only at a new Bourdon tube position. Thus the motorpositions the right-hand end of the floating link 86 to one of twopossible positions corresponding respectively to a desired total steamtemperature standard.

A rate of ow meter 18, measuring the total steam outflow from the vaporgenerator positions a contact member |20 relative to two contactsegments |2|, |22. The contact segments l2 I, |22 are so arranged thatthey are separated from each other by insulating material and may not becontacted simultaneously by the arm |23.

Throughout any predetermined portion of the total load range of thevapor generator the contact arm |20 lwill be in engagement with thecontact segment |2| and throughout another portion of the load range thecontact arm |20 will be in engagement with the contact segment |22. Suchclosure of contact acts to change the temperature standard of the pilotValve assembly 83, `Ell through the agency of the motor ll. In otherwords, the steam temperature control dampers 9, I0 are jointlypositioned through the agency of the pilot stem 88 to maintain one orthe other -of two predetermined temperature standards corresponding todenite ranges of load on the vapor generator. In this particularembodiment the load on the vapor generator is,

of course, represented by the total steam outilow rate passing the oriceI9.

The location and extent of the Contact segments |2l, |22, as well as theadjustments pron vided in connection with the motor Ti, provide that apredetermined superheat or other tain perature of the Vapor outflow willbe maintained throughout a desired portion oi the load range and anotherstandard will be maintained throughout a second portion of the loadrange.

The segment |2| is adapted to be connected through the winding of arelay 80 and a limiting switch 89 to one side oi a power line, while thesegment |22 is adapted to be connected through the winding of a relay'i8 and a limiting switch 68 to the same side of the power line. Thesegments |2| and |22 are both adapted to be connected by the contactorand a push button 8| to the other side of the power line. When thecontactor |20 is first moved into engagement with the segment |22, acircuit is completed from the power line through the push button 8|, thecontactor |20, the segment |22, the winding of the relay 16, and thelimiting switch 88 to the power line again. The relay 18 then operatesto energize the motor so that it rotates in one direction and eventuallyeiects an opening of the limiting switch 88 and a closing of the switch69. The circuit through the relay winding 'l0 is then broken, and therelay operates to open the motor circuit. If the contactor |20 thenmoves into engagement with the segment |2|, a circuit is completed fromthe power line through the push button 8|, the contactor |20, the segment |2|, the winding of the relay 80, and the limiting switch 89 to thepower line again. The relay 8|) then operates to energize the motor forrotation in the opposite direction until it opens the limiting switch 69and closes the switch 88. The push button 8| is arranged to close acircuit lay-passing the contacter |20 and the segment |2| so that themotor `may be caused to operate and establish the same temperaturestandard that would be obtained when the contactor |20 engaged thesegment I2 I Since the contactor |20 is positioned by the meter 78 inresponse to the rate of steam iow in the conduit 244, it will beappreciated that the dampers 9 and I0 will be positioned to maintainsteam temperature standards varying with the rate of steam flow.

It will be appreciated that there may be many modifications andarrangements possible vof the illustrative example given herein, withoutdeparting from the spirit of my invention, and that I have illustratedand described only a preferred embodiment without intending it to belimiting.

This application constitutes a division of my application, Serial No.347,191, iiled July 24, 1940, entitled Control systems, now Patent2,292,023, dated August 4, 1942.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is:

1. In a vapor generator having generating and superheating portionslying in parallel paths conducting heated gases, in combination, dampersarranged in said paths so as to proportion the ow of heated gasestherethrough, iiuid actuated means for positioning said dampers, valvemeans for controlling the supply of pressure fluid to said fluidactuated means, means including an elongated member connected betweenits ends to said valve means for controlling the latter, means sensitiveto the temperature of the vapor leaving the superheater and operativelyconnected to one end of said elongated member, a reversible motorconnected to the other end of said elongated member for moving thelatter to diierent positions, and means for energizing said motor to runfor a predetermined period of time in one direction or the other on apredetermined change in the load conditions on the generator.

2. In a vapor generator having generating and superheating portionslying in parallel paths conducting heated gases, in combination, dampersarranged in said paths so as to proportion the iiow of heated gasestherethrough, iluid actuated means for positioning said dampers, valvemeans for controlling the supply oi pressure fluid to said fluidactuated means, means including an elongated member connected betweenits ends to said valve means for controlling the latter, a reversiblemotor connected to one end of said member, means for energizing saidmotor to run for a predetermined period of time in one direction or theother to move the end of said member to a predetermined position andestablish a temperature standard, and means responsive to thetemperature of the vapor leaving the generator and connected to theother end of said member for maintaining the temperature standardestablished by said motor.

3. The structure of claim 2 in which said motor energizing meanscomprises relays for controlling motor circuits effecting operation ofsaid motor in one direction or the other when energized, limitingswitches operatively connected to said motor, means for connecting saidlimiting switches and said relays in separate circuits from one side ofa power source to separate contact members, and means for connecting theother side of the power source to said contact members in response tothe rate of output of the vapor l generator.

PAUL s. DICKEY."

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,095,767 Adams May 5, 19141,250,332 Fisher 1 Dec. 18, 1917 1,359,042 Doble et al. Nov. 16, 19201,423,764 Greenfield July 25, 1922 1,619,253 Gibson Mar. 1, 19271,729,701 Bennett et al. Oct. 1, 1929 1,748,634 Bucher Feb. 25, 19302,131,058 Lucke Sept. 27, 1938 2,170,345 Bailey et al. Aug. 22, 19392,243,862 Heller June 3, 1941 2,247,884 Kerr et al. July 1, 19412,292,291 Roe Aug. 4, 1942 2,298,700 Junkins et al. -Oct. 13, 1942

